EASA AD 2024-0249
Instruments — Warning Unit Emergency Off Switches — Operational Check
Summary
EASA Airworthiness Directive 2024-0249 is an operational check directive targeting the emergency off switches of warning units installed on Airbus Helicopters Deutschland GmbH EC135, EC635, and MBB-BK117 helicopter models. It mandates repetitive operational checks of these switches to detect mechanical failures that could lead to engine shutdown or fuel shut-off valve issues. The directive applies to all variants and serial numbers of the specified helicopter models.
What Changed
This new Airworthiness Directive introduces mandatory operational checks of the emergency off switches on affected helicopters within 55 flight hours or 12 months after the effective date. It requires additional checks after any emergency off switch activation and mandates replacement or repair if discrepancies are found. Installation of affected parts is allowed only if they pass the operational check before the next flight.
Why It Matters
This directive addresses a critical safety concern involving mechanical failures of emergency off switches that could cause in-flight engine shutdown or loss of fuel shut-off capability. Compliance is essential for operators and maintenance organizations to ensure continued airworthiness and prevent potential accidents. It also impacts parts installation procedures and requires close monitoring of affected components.
What To Do
Operators of EC135, EC635, and MBB-BK117 helicopters with affected warning units must perform an operational check of the emergency off switches within 55 flight hours or 12 months from 2 January 2025. Additional checks are required after any emergency off switch activation. If any issues are detected, the warning unit must be replaced or repaired before the next flight. Installation of affected parts requires passing an operational check prior to flight.